The invention relates generally to IEEE 802.11 wireless networks and, more particularly, medium access protocol for multi-rate IEEE 802.11 wireless networks.
In wireless networks, packets may be corrupted or lost due to various factors, such as path loss, fading and interference. While wireless local area networks (WLANs) conforming to the IEEE 802.11 standard support variable length packets, longer packets may be subject to larger probability of error. The standard defines a process called fragmentation, which produces smaller fragments out of an original frame. Fragmentation increases reliability by increasing the probability of successful transmission of the fragments in cases where channel characteristics limit reception reliability for longer frames. When a frame is received with a length greater than a given fragmentation threshold, the frame is fragmented. In conventional WLANS, the fragmentation threshold is set network-wide. Consequently, when an IEEE 802.11 network supports multi-rate communications, packets with the same size may require different transmit durations at different data rate modes.